1. Field of the Invention
The present invention relates to a shifting means for magnetic head utilized in a flexible disk (hereinafter referred to simply as "floppy") memory system.
2. Description of the Prior Art
In a floppy memory system which is now widely utilized principally as an external memory means for small electronic computers and the like, it is required to contact a thin magnetic material which has been applied on the surface of a disk-shaped Mylar film comprising a floppy being a storage means with a magnetic head, being an electromagnetic converter, by means of a prescribed pressure applied without damaging either the magnetic material and magnetic head. In conventional shifting means, however, it has been difficult to sufficiently comply with such requirement.
More specifically, such a device as described hereinbelow has heretofore been proposed for a type of magnetic head shifting means as mentioned before. Referring now to FIGS. 1 and 2, as well known, a floppy 1 consists of a thin disk-shaped medium 2 having a magnetic substance on both the surfaces thereof and a jacket 3 containing the disk-shaped medium 2. An opening 4 in which magnetic heads 5a and 5b are to be installed is defined on the jacket 3. These magnetic heads 5a and 5b are supported by means of springs 6a and 6b and pressed by the memory medium 2, respectively. One end of an arm 8 is subjected to insert molding by means of injection molding and the like to hold a leaf spring 7 therein, and a surface of the arm 8 is the one for fixing the spring 6a holding the magnetic head 5a. A carriage 20 is guided by means of a guide bar 21 and is movable in radial direction of the memory medium 2 along the guide bar 21. A pedestal 10 for fixing the leaf spring 7 of the arm 8 to the carriage 20 is formed on a side end of the carriage 20. A transverse arm 13 for separating the magnetic head 5a from the memory medium 2 extends from the opposite side end of the arm 8. Furthermore, a coiled spring 15 is interposed between a spring-loaded member 16 and the arm 8 to transfer the latter in a vertical direction with respect to the plane of the memory medium 2, whereby contact of the magnetic heads 5a and 5b with the memory medium 2 is effected with an appropriate pressure. The leaf spring 7 is secured to the pedestal 10 of the carriage 20 by means of the spring-loaded member 16 together with a set-screw 17.
Next, operation of such conventional magnetic head shifting means will be described hereinbelow.
First of all, the transverse arm 13 is lifted to transfer the arm 8 in reverse A direction (FIG. 2) with an amount equal to or more than that of deformation of the springs 6a and 6b in addition to a thickness (=h) of the jacket 3. As the result, a gap equal to or more than the thickness of the jacket 3 can be obtained between the opposed magnetic heads 5a and 5b. Then, the jacket 3 is inserted into the gap between these magnetic heads 5a and 5b to locate the same, and thereafter the medium 2 is rotated around the center thereof.
Then, when the transverse arm 13 is returned along direction A, the magnetic heads 5a and 5b contact with the magnetic material 11 on the medium 2. In such condition as mentioned above, when an electrical signal is given to the magnetic head 5a, magnetic field is generated to magnetize the magnetic material 11 on the medium 2. It is well known that a prescribed information is recorded on the medium 2 in accordance with the manner as described above, whilst such information is read by converting a change in magnetic flux into an electrical signal.
Meanwhile, in such conventional magnetic head shifting means as mentioned above, contact pressure of the magnetic heads 5a and 5b with the magnetic material 11 is derived from reaction force of the compressed coiled spring 15 and kinetic energy of the arm 8 involving the magnetic head 5a effecting rotary motion around the pedestal 10 as the center in direction A. Accordingly, concerning the contact of the magnetic heads 5a and 5b with the magnetic material 11, the kinetic energy and compressive force of the coiled spring 15 become problems in its transient state and its steady state, respectively. In other words, such kinetic energy cannot be reduced, if a special control is not effected for acceleration in the case when the transverse arm 13 is transferred in direction A. In addition, it is self-evident that the state of contacting of the magnetic heads 5a and 5b with the magnetic material 11 in both the transient state and the steady state is different in the case where direction A coincides with gravitational direction, and the case where the reverse A direction coincides with gravitation direction in respect of mass of the arm 8 involving the magnetic head 5a. More specifically, in conventional magnetic head shifting means, compressive force of the coiled spring 15 and acceleration control of the transverse arm 13 must be suitably selected or adjusted every time in accordance with posture and direction in installation of such conventional magnetic head shifting means with respect to gravitational direction.
The disadvantages of a magnetic head shifting means in conventional floppy memory systems have been described hereinbefore.